Finishing-broach



Pawnwdwuay 11, 1920.

F. J. LAPQINTE.

` FINISHING BROACHV.

Aug.

FRANCIS J. LAPOINTE, 0F ANN ABBOR, MICHIGAN.

l FINISHING-BROACH.

Specication of Letters Patent. Patented May 11, 1920.

Application led June 26, 1919. Serial No. 306,993.

To all whom it concern: Be it known that I, FRANCIS J. LAPOINTE,

a citizen of the United States of America, and a resident of Ann Arbor, in the county of 'Washtenaw and State of Michi an, have invented certain new and useful mprovements in Finishing-Broacbes, of which the following isa specification.

This invention relates to broaching tools and particularly to tools of this class desi ed to finish round holes.l

he present invention has for its object the production of a finishing broach by which round holes of any length may be broken surface.

The invention consists in certain novel features of construction 4and arrangement of parts which will be readily understood by reference to the description of the drawings and to the claims to be hereinafter given.

For the purpose of illustrating the invention, one preferred form thereof is illustrated inthe drawings, this form having been found to give satisfactory and reliable results, although it is to be understood that accurately finished leaving a burnished, un-

`the various instrumentalities of which the invention consists can be variously arranged and organized and the lnventlon 1s not llmited to the precise arrangement and organithe scope of the appended claims.

Of the drawings:

Figure 1 represents an elevation of a broaching tool embodying the principles of the present invention.

Fig.A 2 represents an enlarged elevation of a portion of the same and showingthe Vrelative positions of the flattened portions of the cutting members.

Fig. 3 represents an enlarged section 'of the outer end of the tool.

Fig. 4 represents a transverse section on line 4, 4, on Fig., 1 drawn to an' enlarged scale, and

Fig. 5 represents a transverse section on line 5, 5, on Fig. 1 drawn to an enlarged scale.

Similar characters indicate like parts I throughout the several figures of thevdrawn'the drawings, 10 is a member having a cylindrical portion 11 at one end and another cylindrical portion 12 at the opposite end.

The portion 12 is of larger diameter than i the portion 11 and is adapted to burnish the hole when the broaching has been completed. y

The member 10 has two helical cutting members 13, 14 vextending from the cylindrical portion 11 toward the portion 12, the helices of said cutting members gradually increasing in diameter.

Between the portion 12 and the ends of the cutting members 13, 14, are a plurality of annular cutting members 15 having `the same diameter as the portion 12.

The helices 16 of cutting members 13, 14 nearest to the annular members 15 are un- ,broken and continuous and are of the same ldiameter as the diameter of annular mem-l bers 15 and burnishing member 12.

Between the helices 16 and the portion 11, the cutting members 13, 14, have flattened portions 1T disposed at intervals with the flattened portions 17 of one cutting member substantially perpendicular to the Hattened surface 17 of the other member. y

Preferably in each turn of each cutting vmember, there are two flattened surfaces 17 oppositely disposed. The flattened surfaces of the two cutting members are made of such a width that ifin the same plane they would not intersect but would leave a short section of cutting member between the adjacent ends of said flattened surfaces.

The various flattened surfaces which are v in substantial alinement have their ends in overlapping relation to each` other to pre- '1 .distances from the center of the various flattened surfac.

Each cutting member 13, 1 4, is also provided with a plurality of notches 18' which and an imperfect result would be attained.

Owing to the fact that in the present device the cutting members are in ,helical form and two cutting members are 'used with bearing portions in both cutting members oppositely dis'posed and extending the entire length of the work, it is absolutely impossible for the work to get out of alinement while being operated upon lby the tool.

The flattened portions 17 provide spaces which will take care of the chips as the work is being finished, each suchl space providing a place in which the chips cut by sector of cutting member in advance of said portion 17 may find lodgment.

In the operation of the tool, a hole is drilled into the work large enough to' receive the end 11 and then the broach 10 is drawn through the same, the two cuttin members 13, 14, cutting away the roughene surface of the hole until the required diameter is obtained.

The continued movement of the broach 10 through the workwill cause the unbroken helices 16 of the cutting members 13, 14, and the annular cutting members 15 to remove any burs which there may be on the wall of the hole in the work.

l/Vhen the end 12 is drawn through the work, the entire surface .of the hole is burnished and in condition to receive a shaft or other member to be disposed therein.

It is believed that the operation and many advantages of the-invention will be readily understood without further description.

Having thus described my invention,'1 claim- 1I A device of the class described consisting of a -member having a cylindrical portion at one end and a helical cutting member extending therefrom toward the other end and gradually increasing in diameter, said cutting member having flattened portions at intervals.

2. A device of the class described consisting'of a membery having a cylindrical portion at one end and a helical cutting member extendin therefrom toward the'other end and gra uall increasing in diameter, said cutting mem er having flattened porend of the same diameter as the larger diameter of said helical'member.y

4. A device of the class described consisting of a member having a cylindrical portion at one end, a rhelical cutting member extending therefrom toward the other' end and gradually increasing in diameter, and a plurality of annular members at said other end of the same diameter as the larger diameter of said helical member, said helical l member having flattened portions at interva s.

5. A' device of the class described consisting of a member having a cylindrical portion .at one end, a helical cutting member extending therefrom toward the other end and gradually increasing in diameter, and a pluralitylof annular members at `said other end of the same diameter as the larger diameter of said helical member, said helical member having flattened portions at intervals for the greater part of its length with a plurality of continuous unbroken helices at said other end. l

6. A device of the class described consisting of a member having a cylindrical portion at one end, a helical cutting member extendin therefrom Vtoward the other end and gra ually increasing in diameter, and a plurality of annular members at said other end of the same diameteras the lar er diameter of said helical member, said elical member having flattened portions in overlapping relation to each other at intervals for the greater part' of its length with a plurality of continuous unbroken helices vat said other end.

7. A device of the class described consisting of a member having a cylindrical portion at one end and two helical cutting membersextending therefrom toward the otherl en d and gradually increasing in diameter, said cutting members having flattened portions at intervals those of one member substantially perpendicular to those of the other member. 8. A device of the class described consisting of a member having a cylindrical p01'- tion at one end and a helical cutting member extendin therefrom toward the other end and gra ually increasing in diameter, the various helices being provided at intervals'with flattened portions of such a width that if in the same plane their adjacent ends would intersect the` cutting edge at short distances apart.

roo

9. A device of the class described consist ing of a member having a cylindrical portion at one end and two helical. cutting members extending therefrom toward the other end and graduall)Y increasing in diameter said cutting member being provided with flattened portions at right an les to each other and of such a Width that i in the same plane the adjacent ends thereof would intersect the cutting edges at short distances 10 apart.

Signed by me at l Post Oice. Square. Boston. Mass.. this 24th day of June, 1919.

FRAXCIS J. LAPOIXTE.

witnesses ll ALTER E. LOMBARD, NATHAX C. LOMBARD. 

